Disk drives are information storage devices that use magnetic media to store data. A traditional disk drive includes a magnetic disk and a drive arm for driving a HAG with a slider mounted thereon. The disk is mounted on a spindle motor which causes the disk to spin. A primary actuation, such as voice-coil motor (VCM) is provided for controlling the motion of the drive arm and, in turn, controlling the slider to move from track to track across the surface of the disk, thereby enabling the slider to read data from or write data to the disk. In operation, a lift force is generated by the aerodynamic interaction between the slider and the spinning magnetic disk. The lift force is opposed by equal and opposite spring forces applied by the suspension of the HAG such that a predetermined flying height above the surface of the spinning disk is maintained over a full radial stroke of the drive arm.
However, Because of the inherent tolerance (dynamic play) resulting from VCM that exists in the placement of the slider, the slider cannot achieve quick and fine position control which adversely impacts the ability of the slider to accurately read data from and write data to the disk. As a result, a secondary actuation so called dual stage micro-actuator is provided in the HAG in order to improve positional control of the slider.
FIG. 1a illustrates a traditional HAG 277 of a conventional disk drive with such a dual stage micro-actuator 205. The dual stage micro-actuator 205 corrects the displacement of a slider 203 on a much smaller scale, as compared to the VCM, in order to compensate for the resonance tolerance of the VCM and the HAG. The micro-actuator 205 enables, for example, the use of a smaller recording track pitch, and can increase the “tracks-per-inch” (TPI) value by 50% for the disk drive unit, as well as provide an advantageous quickly seeking and/or settle action for HDD and reduction in the head seeking and settling time. Thus, the micro-actuator 205 enables the disk drive device to have a significant increase in the surface recording density of the information storage disks used therein.
Referring to FIGS. 1a and 1b, the micro-actuator 205 has a ceramic U-shaped frame 297 that comprises two ceramic beams 207 with two PZT pieces (not labeled) on each side thereof. The micro-actuator 205 is physically coupling to a suspension 213, and there are three electrical connection balls 209 (gold ball bonding or solder bump bonding, GBB or SBB) to couple the micro-actuator 205 to the suspension traces 210 in one side of the ceramic beam 207. In addition, there are four balls 208 (GBB or SBB) to couple the slider 203 to the suspension 213 in the slider training edge for electrical connection. FIG. 2 shows a detailed process of inserting the slider 203 into the micro-actuator 205. The slider 203 is bonded with the two ceramic beams 207 at two points 206 by epoxy dots 212 so as to make the motion of the slider 203 independent of the drive arm.
When power supply is applied through the suspension traces 210, the PZT micro-actuator 205 can expand or contract to cause the U-shaped frame 297 deform and then make the slider 203 move along a radial direction on the disk 101. Thus a position fine adjustment can be attained.
However, the HAG 277 with the micro-actuator 205 is very difficult to manufacture. At first, inserting and bonding the slider 203 to the micro-actuator 205 is difficult. Secondly, the epoxy dot 212 is very difficult to control, that is, the length and height of the epoxy dot 212 must be controlled in a suitable range for ensuring a good working performance of the HAG 277.
Additionally, the micro-actuator 105 has an additional mass (the U-shaped frame 297), which not only influence the static performance, but also influence the dynamic performance of the suspension 213, such as the resonance performance, so as to reduce resonance frequency and increase the gain of the suspension 213.
Also, because the U-shaped frame 297 of the micro-actuator 205 are very brittle so as to produce a not perfect shock performance. In addition, it is also a other problem that no effective solution to identify the potential micro crack of the U-shaped frame 297. Furthermore, during the voltage applied to the PZT micro-actuator or normal operation, the back and forth bending of the brittle micro-actuator 205 may probably generate the particle and then influence the work performance of the micro-actuator 205.
In the manufacture process of HAG 277, since the HAG 277 has a complex configuration, the slider 203 must tilt during bonding the slider 203 to the U-shaped frame 297, and the U-shaped frame 297 must tilt during bonding the U-shaped frame 297 with the slider 203 to the suspension 213. Both will influence the static attitude of the HAG 277 and accordingly increase the difficulty of manufacturing the HAG 277.
It is well known that polishing is a more effective and widely used cleaning method for the micro contamination in the air bearing surface (ABS) of the slider. However, this cleaning method cannot be used in the above-mentioned HAG 277 because there is a potential danger to damage the U-shaped frame 297 of the micro-actuator 205.
At last, since the slider 203 is supported by the ceramic U-shaped frame 297, it is difficult to ground the slider 203 and suspension to get an electro static discharge (ESD) protection.
Hence it is desired to provide a micro-actuator, head gimbal assembly, disk drive which can overcome the foregoing drawbacks of the related art.